1. Field of the Invention
The present invention relates to a device that tracks the movement of an animal within a research cage and delivers a well controlled and measured shock to the animal's feet. The device also allows the tracking of two animals that can see each other with one of the animals receiving the shocks.
2. Background of the Prior Art
It is often desirable to track the movement of an animal within a research cage while delivering a pain stimulus in order to measure the animal's response to the pain. For example, it may be desirable to track the movements of a mouse while receiving pain stimulus both before and after giving the mouse a newly developed pain medication in order to determine the efficacy of the drug. Of the various types of pain stimulus that can be delivered, a small electric shock of short duration finds favor with many researchers.
In order to deliver these shocks, devices have been proposed wherein a cage is provided, which cage has a grid floor wherein the individual rods forming the grid floor are each electrodes electrically connected to a shock generation device. The test animal stands on some of the rods of the grid floor and electric current is applied across one of the electrodes upon which the animal is standing and a shock is thereby delivered. The problem with the present systems is that they lack knowledge of the location of the test animal on the grid floor. Accordingly, such systems rely on sequentially placing a current onto each rod until a current is placed onto a rod with which the animal is making contact thereby closing an electric circuit and shocking the animal. As such, the delivery of shocks to the animal is dependent on where the animal is standing and is random and therefore not deterministic which contributes to variability of results. An animal will not avoid shock in the same manner in each experiment. However, the sequential placement of the shocks is ordered in some fashion thereby leading to the animal being shocked in differing ways from experiment to experiment. Another problem with such systems is the potential to cause an electric burn to the animal due to high intensity localized power dissipation. For example, a rat may have a high resistance contact with an electrode at its tail. As the shocker applies power to this electrode, a burn can result due to the high voltage and corresponding high power density at this point of contact. Just one watt of power can result in burning a lab animal. Although the goal of the researcher is to deliver a pain stimulus, the researcher does not want to cause injury to the animal.
Accordingly, there exists a need in the art for a device that is capable of delivering a shock to a test animal wherein shock delivery is deterministic in order to have high repeatability between experiment runs. Such as system must be able to determine whereat a test animal is standing so that a shock can be delivered to the animal's foot, yet avoid shocking other body parts of the animal in order to minimize the risk of injury to the animal. Such a system should be of relatively simple design and construction so that it is easy to use and maintain.